can't resolve AppCompatActivity

Question

After renaming application package name, Android Studio displayed this error can't resolve symbol AppCompatActivity

Things I tried:

Clean project
Clean Android Studio cache
Clean Gradle cache
Re-installed IDE
File-> Invalidate cache/restart

But nothing really helped. The project build successfully, but I can not use syntax highlighting.

I used com.android.support:appcompat-v7:23.1.1

Screenshots

At first, you should delete the line with "import android.app.Activity", then check your build.gradle file and make sure your imports are well typed/declared. — Rob, Jan 22 '16 at 13:39
Everything is good in buid.gradle file. compile 'com.android.support:support-v4:23.1.1' compile 'com.android.support:appcompat-v7:23.1.1' — Raman Branavitski, Jan 22 '16 at 13:41
I mean to say, next time, instead of posting images or screenshots of text, please post it as code, because reading images is sometimes difficult. You can format it as code by leaving 4 spaces. By the way, I meant text, not test :-> My mistake. — Box Box Box Box, Jan 22 '16 at 13:51
Try to make a "Sync project with gradle files" in Android Studio, maybe libraries weren't synchronized, and clear those entries : import android.app.Activity import android.support.v7.app.AppCompatActivity; And then add import with ALT+Enter when prompted — Rob, Jan 22 '16 at 14:00
Damn.. When you try to build, what's the error message ? Can you post it here ? — Rob, Jan 22 '16 at 14:03
I dont receive any error messages. Project successfully build and run. But is hard to work cause code completion is not working due to this error. — Raman Branavitski, Jan 22 '16 at 14:07
[Outdated Kotlin Runtime warning in Android Studio](https://stackoverflow.com/questions/43928118/outdated-kotlin-runtime-warning-in-android-studio) was the reason in my case. — Slawa, May 28 '18 at 15:21

score 82 · Answer 1 · answered Apr 15 '16 at 08:15

82

Okay, to anybody who might stumble upon this now, Android Studio is very, very, very weird.

Solution : Go to your build.gradle file and in your dependencies find the appcompat one, something like compile 'com.android.support:appcompat-v7:XX.X.X'

Change it to compile 'com.android.support:appcompat-v7:XX.X.+'

Then click on Sync Now on the top right of the editor. All the red squiggly lines should go if everything else in your code is correct.

Then go back to your build.gradle and change it back to whatever it was and click Sync Now

It should all be fine given that you have the latest version of everything or close to it.

answered Apr 15 '16 at 08:15

4127157

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wow, I can't believe this solution is actually works. I spent half hour try to solve this. ty. – Ryde Jun 13 '16 at 06:46
@IgorGanapolsky I do not know, it means the latest version of whatever is the current, some weird Android Studio bug. – 4127157 Dec 28 '16 at 17:03
if i add compact-v7 in build.gradle showing no resource in ui elements errors before that project in eclipse to studio migrated project now am plan to update with new version in that time we are using Activity now plan for AppCompactActivity with ToolBar and material designing updates and at that time google play services as lib added now how can i add google play services in build.gradle i have so many doubts and confusions from eclipse migrated to studio old project. – Harsha Jan 23 '17 at 11:22
@Harsha You need to clean project and rebuild, it should work. – 4127157 Jan 26 '17 at 21:55
3

I had the same problem and just had to press the "Sync Project with Gradle Files" without making any changes to anything. I think my issue arises from transferring between machines using github repos. – musterjunk Aug 05 '17 at 19:16
@musterjunk That solves the problem for some but in my case it didn't so I found this. – 4127157 Aug 06 '17 at 12:14
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I had the problem where it said the cannot find symbol but it allowed to build and run... i just had to sync this file again thanks a ton! – Crazy Alien Nov 01 '17 at 09:41
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I had to replace the entire version with a plus sign, not just the last X – Impulse The Fox Jul 27 '18 at 13:19

score 64 · Answer 2 · answered Jul 13 '17 at 12:10

64

Lets get going step by step: first clean project by using

Build->Clean

if this doesn't helps then use your second weapon

File>Invalidate Caches/Restart...

But the real problem begins when all the above options doesn't works so use your ultimate weapon close project and go to project location directory and delete

.idea

You can open your project now again. This worked for me and problem comes most often when you are working with VCS. And this problem is not associated with android component classes but also to the libraries, both shows the same error.

answered Jul 13 '17 at 12:10

vikas kumar

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Thank you very much, the deleting .idea worked! I spent more than 2 hours with experimenting to solve this problem and fortunately I found your solution. Android Studio 2.3.3 – Zsivics Sanel Jul 24 '17 at 20:31
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Thank you, this is the only solution that worked in my case! – XIII May 06 '18 at 18:41
Thanks! This solved my problem, Android Studio was importing only some packages of support library, weird... – rafael Aug 03 '18 at 18:50
This didn't work for me. what worked was to add + in my grade dependancy of appcompat, – Dilip Agheda Aug 13 '18 at 02:13
Deleting .idea folder worked for me too, while other solutions didn't – Andreas Oikonomou Sep 26 '18 at 10:44
This worked for me with the additional step: Upon reopen of the project I still had compilation errors - hovering over the red code marked as unresolved, hitting 'alt+enter' to reapply the imports worked for me. – Kai Nov 03 '18 at 11:15

Sushin Pv · Answer 3 · 2018-05-14T09:54:44.340

24

I was having the same issue, but when I did Invalidate cache/restart option it worked fine for me.

First try to clear all your build files

Build->Clean

if it doesn't work try this option

File -> Invalidate cache/Restart

edited May 14 '18 at 09:54

answered Oct 11 '16 at 14:54

Sushin Pv

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Perfect! Perfect! Perfect! The right answer and simple. This usually happens when you hop around different projects. – Vijay Kumar Kanta Feb 13 '18 at 14:20

score 9 · Answer 4 · answered Jun 25 '18 at 19:57

If methods like

Clean project

Clean Android Studio cache

Clean Gradle cache

Re-installed IDE

File-> Invalidate cache/restart

do not work. use this method to resolve your issue.

Exit Android Studio

Navigate in your project to the .idea folder

Remove .idea folder

Restart Android Studio.

Thats it.

score 6 · Answer 5 · answered Jul 27 '19 at 06:01

6

The issue could be import reference, try changing it.

From:

import android.support.v7.app.AppCompatActivity;

To:

import androidx.appcompat.app.AppCompatActivity;

answered Jul 27 '19 at 06:01

CodeSlave

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score 5 · Answer 6 · answered Mar 14 '17 at 16:17

5

For me was enough to go on: - Tools > ANDROID > SYNC PROJECT WITH GRADLE FILES

answered Mar 14 '17 at 16:17

Blasco73

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This solution worked for me. It seems the activity could not find references to the `appcompat` library – William Jun 02 '17 at 08:33
This also helped me a lot.Thanks for this suggestion – priyanka Mar 05 '18 at 07:32

score 4 · Answer 7 · answered Feb 07 '16 at 00:07

4

I was having this exact same issue just a couple minutes ago and fixed it by doing a Build > Rebuild Project.

Hope it helps.

answered Feb 07 '16 at 00:07

McSullivan

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score 2 · Answer 8 · answered Feb 08 '16 at 12:46

2

Only removing whole .gradle folder helped me.

answered Feb 08 '16 at 12:46

Raman Branavitski

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Tried everything above, but this end up worked for me. – loveNZ May 28 '18 at 20:39

score 2 · Answer 9 · answered Apr 13 '18 at 00:26

This is what worked for me, strangely enough:

Change implementation 'com.android.support:appcompat-v7:26+' to implementation 'com.android.support:appcompat-v7:26.0.1'
Go to File → Invalidate Caches/Restart
Wait for the Gradle sync to finish on restarting. Once it does you will be prompted to add the Google maven support repository. Click on the corresponding link, and let Gradle resolve the dependencies.
The errors should be gone now

FWIW, in my case the issue occured after moving my Android Studio installation to a new machine and upgrading to AS 3.1.

score 2 · Answer 10 · answered Apr 17 '18 at 16:42

2

Deleting the ".idea" folder worked for me. As mentioned above by Vikas Kumar

Then I using this to fix the "SDK location error"

answered Apr 17 '18 at 16:42

Omphile

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First I clean the project, after remove all .idea folders and finally Invalidate/Restart – Cami Rodriguez Jun 03 '18 at 16:08

score 2 · Answer 11 · answered Jun 17 '18 at 13:54

You got error like

1.First you have to clean project after that same issue got then

2.check library minimum compile "com.android.support:appcompat-v7:22.1.0"

Check library does not use two or more times
Remove multiple time usage of library dependency
Clean and Rebuild Project to a got solution

score 2 · Answer 12 · answered Sep 21 '18 at 10:47

I was stuck with this problem and its take me whole day to solve this.Finally i solved this with the following steps

Close your android studio
Go to you project folder and look for .idea folder
Find libraries folder and rename it
Then start your Android studio and open that project again.

Thats it.

score 1 · Answer 13 · answered Sep 14 '17 at 07:14

1

I had the same issue and the following worked for me

File -> Invalidate cache/Restart

There is some kind of caching issue that is happening. If such kind of issue appears try this since most of the time it will work :D

answered Sep 14 '17 at 07:14

Nauman Shah

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score 1 · Answer 14 · answered Oct 19 '17 at 05:29

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i have this problem while using the android studio on ubuntu 16.04 go to File>invalid cache/Restore>Invalidate and Restart that works fine for me

answered Oct 19 '17 at 05:29

score 1 · Answer 15 · answered Oct 28 '17 at 13:16

Go to your build.gradle file and in your dependencies find the appcompat one, something like compile 'com.android.support:appcompat-v7:25.X.X' Change it to compile 'com.android.support:appcompat-v7:25.3.+' Then click on Sync Now on the top right of the editor. Then go back to your build.gradle and change it back to whatever it was and click Sync Now This worked for me.

score 1 · Answer 16 · answered Apr 05 '18 at 19:11

This working for me, on macOS:

go to, Android Studio -> Preferences -> Appearance & Behavior -> System Settings -> Android SDK -> SDK Platforms And download Android SDK Platform XX and Sources for Android XX. Where XX es the value of compileSdkVersion on your gradle (Module:app)

on Windows the route is: File -> Settings... -> Appearance & Behavior -> System Settings -> Android SDK -> SDK Platforms

score 1 · Answer 17 · answered Apr 16 '18 at 12:32

If all attempts failed (invalidate cache, clean and rebuild, restart,...), close Android Studio (maybe just close the project), run any file manager, go to project folder, find .idea/libraries folder and delete its content (list of xml files). After new start AS or opening project the problem should be resolved.

score 1 · Answer 18 · answered Apr 24 '18 at 11:31

head over to build.gradle(module app)

if you hover your mouse over to com.android.support:appcompat a popup will say new version is available just replace in the existing version number with the new version number press sync now and you are good to go p.s nothing else worked for me on 2 pc's

score 1 · Answer 19 · answered Jun 05 '18 at 06:43

1

In Android Studio 3.1.2, I have the same issue After renaming application package name. The following worked for me:

Deleting the ".idea" folder, Then File -> Invalidate Caches/Restart.

answered Jun 05 '18 at 06:43

Javan

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score 1 · Answer 20 · edited Jun 11 '18 at 22:06

I've noticed that Android Studio 3.1 doesn't pull in the support libraries seamlessly. Here's how to trigger it. Update the support library version to 27.x.x newer version (you can get the new version info by mouse hover over the version number next to implementation under dependencies ) manually in the module's build.gradle file under dependencies. Then re-sync the project. Find the Visual Solution(Image) from this Link

score 1 · Answer 21 · answered Aug 23 '18 at 13:50

This usually happens when you open any old project. Open your Build.gradle (app module) file and update the dependencies to the latest version which you can find in any recently created project or create a new project and copy the dependencies. Sync and then clean your project.

EX: Older versions--> compile 'com.android.support:appcompat-v7:24' Update to latest version--> implementation 'com.android.support:appcompat-v7:28.1.1'

score 1 · Answer 22 · answered Sep 08 '18 at 06:19

1

If the methods via gradle file / "Invalidate caches" do not work, use this way:

Navigate in your project to the .idea folder
Just Rename the libraries folder
Restart Android Studio. It will recreate the libraries folder and work again.

answered Sep 08 '18 at 06:19

Shubham Goel

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score 1 · Answer 23 · answered Sep 24 '18 at 20:32

Guys I know this is gonna sound stupid but I only switched my project like I had 2 projects in my system so I opened the other project when it was completely ready I clicked on open to open my actual project and it worked so just try to switch projects and re open it, this should sort out your issue.

score 1 · Answer 24 · edited Jun 20 '20 at 09:12

1

Easy

Open app level build.gradle
Remove appcompact-v7 dependency & Sync.
Add dependency again & Sync.

Error is no more! :)

Before

After

edited Jun 20 '20 at 09:12

Community

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answered Nov 22 '18 at 11:36

Khemraj Sharma

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score 1 · Answer 25 · answered Nov 24 '18 at 00:49

1

Close your project using FILE -> CLOSE PROJECT and then Open, worked for me fixed all the issues.

answered Nov 24 '18 at 00:49

Mohammad Abraq

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score 1 · Answer 26 · answered Dec 19 '18 at 18:40

I tried deleting the .idea folder, Clean Build, Validate Caches / Restart, changing Build Tools vers... None of them worked for me.

I solved this error with selecting the red underlined codes then pressing Alt+Enter and selecting the Import Class option. It changes the imports to **androidx.core.*******. If you do this to all your red underlined codes your errors should have resolved.

score 0 · Answer 27 · edited Mar 07 '17 at 10:14

0

I've updated appcompat library from version 25.0.1 to 25.1.0

In gradle:

from: com.android.support:appcompat-v7:25.0.1

to: com.android.support:appcompat-v7:25.1.0

Everything works well now.

edited Mar 07 '17 at 10:14

Matteo Baldi

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answered Mar 07 '17 at 09:45

Nicola Gallazzi

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score 0 · Answer 28 · edited Feb 15 '18 at 08:42

0

When all your dependencies and SDK tools are in-line and it still is giving sync error. Add this code in your build.Gradle and sync it:

allprojects {
    repositories {
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
}

Also like to point, before doing this I tested all tricks mentioned here. But only this worked for my Android (2.3) - Feb'17 release.

edited Feb 15 '18 at 08:42

piet.t

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answered Feb 12 '18 at 04:22

Rohit Sharma

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Yes. Thanks @EnamulHaque I know, I'm yet to upgrade my version. That's Feb'17 Android Studio release version. Hope it helps someone. – Rohit Sharma Feb 12 '18 at 05:27

score 0 · Answer 29 · edited Jun 20 '18 at 18:48

0

With the new Release of android studio 3.1.3, you must put this code inside build.gradle.

implementation 'com.android.support:design:23.4.0'

edited Jun 20 '18 at 18:48

Fabulous

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answered Jun 20 '18 at 17:44

alaa

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Dhruv Parmar · Answer 30 · 2019-03-20T16:14:44.967

0

Open build.gradle file and in your dependencies and

Change file with

implementation 'androidx.appcompat:appcompat:1.0.0-beta01'

This worked for me..

edited Mar 20 '19 at 16:14

answered Mar 20 '19 at 15:36

Dhruv Parmar

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Hello and welcome! What does this answer provide that the highest voted one does not already provide? https://stackoverflow.com/a/36641765/10747134 It seems like most of it was copied and pasted from there as well. – Mar 20 '19 at 15:58

score 0 · Answer 31 · answered Apr 02 '19 at 06:20

0

I had the same issue and it resolved by installing build-tools library.

answered Apr 02 '19 at 06:20

Masood Anwar

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score 0 · Answer 32 · answered Apr 15 '19 at 08:17

recently I encountered this problem, I used java code and Kotlin in the development of my application. I really spent a lot of time searching for the cause of the problem. I tried everything in this comment but the problem still doesn't go away, and the program can't be run yet.

so the problem I have is about the Kotlin version of the project that doesn't match the version that is in the android studio framework.

when I equate it, the problem disappears and the program runs again. Hope this helps.

score 0 · Answer 33 · answered Sep 14 '19 at 02:26

0

I was having the same issue, but when re-built project it worked fine for me.

answered Sep 14 '19 at 02:26

Kulwant

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score -1 · Answer 34 · answered May 21 '19 at 11:09

Try first these both solution: 1. File >> Invalidate Caches / Restart and

Change implementation 'com.android.support:appcompat-v7:XX.X.+' to implementation 'com.android.support:appcompat-v7:XX.X.+'

If above both solution doesn't work ,try this it surely work, it work for me even

i) Exit the Android studio.

ii) Go to your project directory.

iii) Find the .idea folder in your project directory.

iv) Delete .idea folder.

v) Start your android studio.

score -2 · Answer 35 · edited Apr 14 '18 at 09:37

-2

This sometimes happens when you import some other projects in your IDE.
In that case try Building your project 2 to 3 times it automatically gets resolved.

For Rebuild you need to follow the following path:

Build-> Rebuild Project

edited Apr 14 '18 at 09:37

Mark Rotteveel

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answered Apr 14 '18 at 05:43

Navneet

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can't resolve AppCompatActivity

35 Answers35

Easy

Before

After

Linked